Doctor not looking into my condition serious enough?

Last year, I had a bp of 130/70 and when I went in for my physical this year, it was a 144/70. My doctor instantly prescribed medication with just using the blood pressure monitor and I was wondering if she's looking into this enough? This is a huge deal and once I start taking meds, I will have to take them forever. I'm currently 17 years old and in perfect shape. Family does have a history of hypertension. Should I take a blood test to see if I actually have high blood pressure? It really doesn't seem right to just trust the doctor when they've only used a bpm.